Go through these in order and stop at the first one that applies. If you are reading this for someone else, answer for them.
1
Is any of this happening now?
Call 911
Call emergency services if your baby has a seizure, becomes unresponsive, turns blue, has serious breathing difficulty, or has repeated pauses in breathing.
If you have been given an emergency hypoglycaemia plan, follow it while help is being arranged.
A home glucose result should not delay emergency care for a baby with serious symptoms.
And for anyone, someone who:
is bleeding heavily and it will not stop with firm pressure
Other emergency signs, for anyone
Someone who is struggling to breathe, gasping, choking, or cannot get words out
Someone who has chest pain, tightness or pressure lasting more than a few minutes
Someone who has sudden weakness or drooping on one side of the face or body, slurred speech, or sudden confusion
Someone who is unconscious, or cannot be woken
Someone who has had a seizure that will not stop, or does not wake up afterwards
Someone who has lips or skin that look pale, blue, grey or blotchy
Someone who you believe has taken an overdose or swallowed something poisonous
2
Is any of this happening?
Be seen today
While your baby is in hospital, tell the newborn care team immediately if your baby becomes unusually shaky, cold, difficult to wake, or unable to feed.
Do not wait for the next planned glucose check.
Seek urgent medical assessment for a newborn who:
Is feeding much less than usual or repeatedly cannot finish feeds
Is unusually sleepy, floppy, jittery, or difficult to wake
Has repeated vomiting or seems increasingly unwell
Has an abnormally low temperature
Has known hypoglycaemia and readings below the baby's discharge plan
The article also says
Symptoms in a newborn can worsen quickly and may have causes other than low blood sugar.
Every sign above is quoted from the sofidex article on Low blood sugar - newborns. If you are not sure, err upward — it is always reasonable to be checked.